Clostridium difficile (C. difficile) is a gram-positive anaerobic bacillus and one of the most frequently recognized bacterial causes of diarrheal disease in hospitalized adults in industrialized countries. The microorganism can be acquired nosocomially and is present in environmental sources. Antibiotic-associated colitis and pseudomembranous colitis are frequently associated with cytotoxigenic C. difficile. The frequency of C. difficile toxin associated with antibiotic-associated colitis is 50-80% and with pseudomembranous colitis is 90-100%.
Despite available treatment for antibiotic-associated colitis and pseudomembranous colitis, relapses occur in 20-25% of patients. Vancomycin and metronidazole can be effective, but treated subjects are prone to relapse. Other treatment modalities include tolevemer, a toxin binding polymer (Louie et al. (2006) Clin. Infect. Dis. 43:411), and an antiparasitic medication, nitazoxanide (Med. Letter Drugs Ther. (2006) 48:89). Since relapses are so common, there is still a need for additional effective treatment and prevention of C. difficile-associated disease, particularly in humans.